In a chain welding machine of this type known from German published unexamined patent application 2,457,180, the kinematic chain of elements begin at a nonpositive cam mechanism with a camshaft-mounted disk cam which actuates the control lever. A hydraulic cylinder serving as a link of the kinematic chain of elements is disposed between two other, adjacent links of this chain and connected to both. As a result, the contact pressure exerted on each other by the two wire ends of the chain link to be welded is nearly constant from one link to the next regardless of the tolerances in the dimensions and strength values of the links of a given chain strand, and the weld quality therefore remains constant.
This is accomplished also with the chain welding machine proposed in patent application P 26 45 719.2-14 of the Applicant, which corresponds to U.S. patent application Ser. No. 839,391, now U.S. Pat. No. 4,139,982, which moreover requires less maintenance and reliably maintains a predetermined contact pressure. In this machine, which has no accumulator and has a single-acting hydraulic cylinder, the supply line to the latter is interrupted by a safety relief valve and a pressure-regulating valve and is connected to a hydraulic pump moving a hydraulic fluid.
However, both the prior-art machine and the machine proposed by the Applicant are unable, because of the non-positive connection at the cam mechanism produced by springs at least in the machine proposed by the Applicant, to permit a definite, reproducible adjustment of the contact pressure with time as a function of the changing normal dimensions, shapes and materials of the links of different chain strands that would vary from one chain strand to the next. Hitherto this has been possible only with fully hydraulic machines, which are considerably more complicated with respect to construction and control than the essentially mechanical machines of the type to which the invention relates.